This work helped further theBig Bang theory of the universe using theCosmic Background Explorer.[5] According to the Nobel Prize committee, "the COBE project can also be regarded as the starting point forcosmology as a precision science."[6] In 2007, Smoot donated $500,000 to fund the Berkeley Center for Cosmological Physics,[7] and an additional amount from his Nobel Prize money, less travel costs, to the East BayCommunity Foundation, a charity.[8]
Smoot switched to cosmology and began work at Berkeley, collaborating withLuis Walter Alvarez on the High Altitude Particle Physics Experiment, astratosphericweather balloon designed to detectantimatter in Earth's upper atmosphere,[18] the presence of which was predicted by the now discreditedsteady state theory of cosmology.
He then took up an interest incosmic microwave background radiation (CMB), previously discovered byArno Allan Penzias andRobert Woodrow Wilson in 1964. There were, at that time, several open questions about this topic, relating directly to fundamental questions about the structure of theuniverse. Certain models predicted the universe as a whole was rotating, which would have an effect on the CMB: itstemperature would depend on the direction of observation. With the help of Alvarez andRichard A. Muller, Smoot developed a differentialradiometer which measured the difference in temperature of the CMB between two directions 60 degrees apart. The instrument, which was mounted on aLockheed U-2 plane, made it possible to determine that the overall rotation of the universe was zero, which was within the limits of accuracy of the instrument. It did, however, detect a variation in the temperature of the CMB of a different sort. That the CMB appears to be at a higher temperature on one side of the sky than on the opposite side, referred to as a dipole pattern, has been explained as aDoppler effect of the Earth's motion relative to the area of CMB emission, which is called thelast scattering surface. Such a Doppler effect arises because the Sun, and in fact theMilky Way as a whole, is not stationary, but rather is moving at nearly 600 km/s with respect to the last scattering surface. This is probably due to thegravitational attraction between our galaxy and a concentration of mass like theGreat Attractor.[18]
At that time, the CMB appeared to be perfectly uniform excluding the distortion caused by the Doppler effect as mentioned above. This result contradicted observations of the universe, with various structures such asgalaxies andgalaxy clusters indicating that the universe was relativelyheterogeneous on a small scale. However, these structures formed slowly. Thus, if the universe is heterogeneous today, it would have been heterogeneous at the time of the emission of the CMB as well, and observable today through weak variations in the temperature of the CMB. It was the detection of these anisotropies that Smoot was working on in the late 1970s. He then proposed toNASA a project involving asatellite equipped with a detector that was similar to the one mounted on the U-2 but was more sensitive and not influenced byair pollution. The proposal was accepted and incorporated as one of the instruments of the satelliteCosmic Background Explorer (COBE), which cost $160 million. COBE was launched on November 18, 1989, after a delay owing to the destruction of theSpace Shuttle Challenger. After more than two years of observation and analysis, the COBE research team announced on April 23, 1992, that the satellite had detected tiny fluctuations in the CMB, a breakthrough in the study of the early universe.[19] The observations were "evidence for the birth of the universe" and led Smoot to say regarding the importance of his discovery that "if you're religious, it's like looking at God."[20][21]
The success of COBE was the outcome of extensive teamwork involving more than 1,000 researchers, engineers and other participants. John Mather coordinated the entire process and also had primary responsibility for the experiment that revealed the blackbody form of the CMB measured by COBE. Smoot had the main responsibility of measuring the small variations in the temperature of the radiation.[22]
Smoot collaborated withSan Francisco Chronicle journalist Keay Davidson to write the general-audience bookWrinkles in Time, that chronicled his team's efforts.[23] In the bookThe Very First Light, John Mather and John Boslough complemented and broadened the COBE story,[24] but also suggested that Smoot violated team policy by leaking news of COBE's discoveries to the press before NASA's formal announcement, a leak that, to Mather, smacked of self-promotion and betrayal. Smoot eventually apologized for not following the agreed publicity plan and Mather said tensions eventually eased. Mather acknowledged that Smoot had "brought COBE worldwide publicity" the project might not normally have received.[25]
After COBE, Smoot took part in another experiment involving a stratospheric balloon,Millimeter Anisotropy eXperiment IMaging Array, which had improved angular resolution compared to COBE, and refined the measurements of the anisotropies of the CMB. Smoot has continued CMB observations and analysis and was a collaborator on the third generation CMB anisotropy observatoryPlanck satellite. He was also a collaborator of the design of theSupernova/Acceleration Probe, a satellite which is proposed to measure the properties ofdark energy.[26] He has also assisted in analyzing data from theSpitzer Space Telescope in connection with measuringfar infrared background radiation.[27]
Smoot was credited byMickey Hart with inspiring the albumMysterium Tremendum, which is based, in part on "sounds" that can be extracted from the background signature of the Big Bang.[28]
On September 18, 2009, Smoot appeared on an episode of theFox television showAre You Smarter Than a 5th Grader? During filming, he reached the final question, "What US state is home toAcadia National Park?", to which he gave the correct answer "Maine", becoming the second person to win a million-dollar prize.[7][34]
On December 10, 2009, he appeared in aBBC interview of Nobel laureates, discussing the value science has to offer society.
^Bourzac, Katherine (January 12, 2007)."Nobel Causes".Technology Review. Archived fromthe original on January 29, 2012. RetrievedSeptember 5, 2007.And Smoot himself can still vividly recall playing a practical joke on his graduate thesis advisor, MIT physics professor David Frisch.
^"The Nobel Prize in Physics 2006" (Press release). The Royal Swedish Academy of Sciences. October 3, 2006. Archived fromthe original(PDF) on August 15, 2010. RetrievedOctober 5, 2006.
^"The SMOOT as unit of Length".aether.lbl.gov. Lawrence Berkeley National Laboratory.Archived from the original on September 8, 2025. RetrievedMarch 24, 2022.
^Yarris, Lynn (October 26, 2006)."After the Phone Call".Science@Berkeley Lab. Lawrence Berkeley National Laboratory. Archived fromthe original on May 6, 2008. RetrievedSeptember 5, 2007.
George Smoot on Nobelprize.org including the Nobel Lecture December 8, 2006Cosmic Microwave Background Radiation Anisotropies: Their Discovery and Utilization
